Where Should You Look for Mouse Entry Points Around a Buckden Property?

This is the fact that reframes the whole search, and once you have it the question stops being whether your building has a gap and becomes which one they are using.

Five Millimetres

BPCA state it precisely: mice only need a gap of 5mm to gain entry, roughly the diameter of the eraser end of a pencil.

Hold a pencil up and look at the eraser end. That is the search. Every building has openings that size, which is why the useful question is never whether there is a way in.

What 5mm Looks Like in Practice

• The gap around a pipe where the filler has shrunk back or cracked
• A hairline opening under a door, where a threshold has worn
• A missing chip of mortar at a perpend joint
• The slot in a plastic air brick cover that has cracked
• A gap at the corner of a soffit joint
• The clearance around a cable entering through a wall
• A shrinkage crack where a modern extension meets an older wall
• The gap under a garage door, which is rarely 5mm and usually more

The Other Thing People Get Wrong

Mice climb, confidently. A gap at roof level is as usable as one at the doorstep, reached from a fence, a drainpipe, a climbing plant or an overhanging branch. So a search that only covers ankle height covers about half the building.

They also travel a long way inside a structure once they are in it. A mouse seen in a first-floor bedroom may have entered at ground level forty feet away, through a cavity, a service riser or a floor void — which is why the place you see one is frequently nowhere near the place it came in.

How to Search Properly

1. Take a torch and hold it low, raking across the surface rather than pointing straight at it. Shallow gaps and smearing show in raking light and vanish in flat light.
2. Go slowly, all the way round the outside, at ankle height first.
3. Then look up: eaves, soffits, verges, vents, and anything that reaches the roof.
4. Look for smearing at the edge of any opening — that is as close to proof as this gets.
5. Note everything, and seal nothing yet. Proofing comes after the property is confirmed clear.

Where you cannot find it, that is normal and it is a large part of what a survey is for. A pest inspection and survey is a fixed cost and covers inside and outside.